/* Copyright (c) 2010, Carl Burch. License information is located in the
 * com.cburch.logisim.Main source code and at www.cburch.com/logisim/. */

package com.cburch.logisim.std.gates;

import java.awt.Graphics;

import com.cburch.logisim.analyze.model.Expression;
import com.cburch.logisim.analyze.model.Expressions;
import com.cburch.logisim.data.AttributeSet;
import com.cburch.logisim.data.Value;
import com.cburch.logisim.instance.Instance;
import com.cburch.logisim.instance.InstancePainter;
import com.cburch.logisim.instance.InstanceState;
import com.cburch.logisim.tools.WireRepairData;
import com.cburch.logisim.util.GraphicsUtil;
import static com.cburch.logisim.util.LocaleString.*;

class XorGate extends AbstractGate {
    public static XorGate FACTORY = new XorGate();

    private XorGate() {
        super("XOR Gate", getFromLocale("xorGateComponent"), true);
        setAdditionalWidth(10);
        setIconNames("xorGate.svg", "xorGateRect.svg", "dinXorGate.svg");
        setPaintInputLines(true);
    }

    @Override
    public String getRectangularLabel(AttributeSet attrs) {
        if (attrs == null) {
            return "";
        }

        boolean isOdd = false;
        Object behavior = attrs.getValue(GateAttributes.ATTR_XOR);
        if (behavior == GateAttributes.XOR_ODD) {
            Object inputs = attrs.getValue(GateAttributes.ATTR_INPUTS);
            if (inputs == null || ((Integer) inputs).intValue() != 2) {
                isOdd = true;
            }
        }
        return isOdd ? "2k+1" : "=1";
    }

    @Override
    public void paintIconShaped(InstancePainter painter) {
        Graphics g = painter.getGraphics();
        GraphicsUtil.drawCenteredArc(g,   2, -5, 22, -90,  53);
        GraphicsUtil.drawCenteredArc(g,   2, 23, 22,  90, -53);
        GraphicsUtil.drawCenteredArc(g, -10,  9, 16, -30, 60);
        GraphicsUtil.drawCenteredArc(g, -12,  9, 16, -30, 60);
    }

    @Override
    protected void paintShape(InstancePainter painter, int width, int height) {
        PainterShaped.paintXor(painter, width, height);
    }

    @Override
    protected void paintDinShape(InstancePainter painter, int width, int height,
            int inputs) {
        PainterDin.paintXor(painter, width, height, false);
    }

    @Override
    protected Value computeOutput(Value[] inputs, int numInputs,
            InstanceState state) {
        Object behavior = state.getAttributeValue(GateAttributes.ATTR_XOR);
        if (behavior == GateAttributes.XOR_ODD) {
            return GateFunctions.computeOddParity(inputs, numInputs);
        } else {
            return GateFunctions.computeExactlyOne(inputs, numInputs);
        }
    }

    @Override
    protected boolean shouldRepairWire(Instance instance, WireRepairData data) {
        return !data.getPoint().equals(instance.getLocation());
    }

    @Override
    protected Expression computeExpression(Expression[] inputs, int numInputs) {
        return xorExpression(inputs, numInputs);
    }

    @Override
    protected Value getIdentity() { return Value.FALSE; }

    protected static Expression xorExpression(Expression[] inputs, int numInputs) {
        if (numInputs > 2) {
            throw new UnsupportedOperationException("XorGate");
        }
        Expression ret = inputs[0];
        for (int i = 1; i < numInputs; i++) {
            ret = Expressions.xor(ret, inputs[i]);
        }
        return ret;
    }
}
